Device for making precision adjustments



May 4 1926. 1,583,281

E. K. CURTIS 4 nsvxcs FOR MAKING pnsczsron ADJUSTMENTS Filed May 1924A/MTORNEYS Patented May 4, 1926.

UNITED STAT snwaasx. deems, onianoonhrn', roan", Ass'reironTosmiinrAo'rUnnIts Afirn 1 PATENT OFFICE.-

rnvnnron's ELECTRIC COMPANY, 01* Yeas, n. Y.,- A CORPORATION OF NEWYORK.

Device roe meme rnncrsrOn Amusements Application filed ma as,

To all whom it may concern.

Be it known that I, EDWARD K; GUR'IIS, a citizen of the United States,residing at 1735 West 11th treet, Brooklyn, in'ther county of Kings,State of New York, have invented certain new and useful Improve ments inDevices for Makiiig Precision Ad justments; and I do hereby declare thefollowing to be a full, clear, and exact description Of'the invention,such as will enable others skilled in the art towhich it appertains tomake and: use the same.

This invention relates to a device for making precision adjustments, andparticularly to one adapted for use in radio tuning.

In making precision adjustments of delicate instruments, such as thevariable condensers, variometers,variocouplers, etc., used in radio,direct manipulationis at best unsatisfactory and cannot well be employedwhere the instrument must be set Within a fraction of a degree; Wherethe shaft of the instrument is tightly journaled, it is practicallyimpossible to make nice adjustinents by turning the knob or dialdirectly with the fingers, for the instrument does not turn smoothly butby a series of jerks, any one of which is greaterthan the preciseincrement desired. lVhen the shaft is loosely journaled, precise digitaladjustment, a-l- I though easier of attainment than when'the instrumentdoes not turn readily, is still difficult enough, and besides theadjustmentonce made is not permanent and is easily lost throughvibration. I am aware that Va? rious de ices have been designed toovercome these objectionable features, but thosewhich have beensuccessful have been complicated and expensive, and in the case of radioreceiving sets not readily adaptable for use on sets already built andin operation.

It is, therefore, the object of the present invention to provide asimple and inex'pen sive device for making and maintaining pre cis ionadjustments, without interfering or slowing up approximate adjustments,particularly designed for radio receiving sets, and adapted to be usedin connection with the ordinary tuning dials now in common use, so thata set-may be readily equipped with these adjusting devices, at smallexpense and with little labor. I- have attained this object intei'posingbetween the dial and the panel an element which makes fric- 1924. SerialNo. 715,259.

tional contact with the diahbut which does not interfere with the largeapproximate adjustingmovements made directly with the fingers, andprovidingsome gear reducing mcanssueh as a. screw Or wormand wheel [Thenature of the invention will bemore clearly understood aftera study ofthe accompanying drawing which illustrates a preferred embodiment of it,as applied to. a radio 'receiving sct; In this drawing, Fig. 1

is, a plan View of a portion of a panel on which the precision adjustingdevice of the present invention is mounted, the dial of the instrumentto adjusted being removed, audits position indicated by dot anddashline; Fig.- 2 is a section taken along line 2-2 of- Fig. 1 showingftheprecision adjusting device and the dial of the instrument in operativeposition; and Fig. 3 is a detailof the actuating element ofthefprecision device taken along line 3-3 of .1.

.In these drawings, I represents the usual panel of. a radio receivingset upon which the. various instruments are mounted, and 2 representsthe shaft of one -,of these instruments shown in its usual position,projectingoub war'clly'through the panel. Rotation of this shaft andconsequent adjustment of the in-- strument is ordinarily effected bymeans of a dial 3, which isadjustably mounted uponthe end of the shaft 2by means of av set screw 4c, This dial is provided with the usualknurled'head or knob 5 and the usual indicia (not shown) upon itsbeveled peripheral face 6, thesetting of the instrument being'readagainst a pointer line 7 on the panel. The construction describedabove is the usual and ordinary construction found in radio receivingsets, and I shall now pro ceed to describe the precision adjusting de-'vice ofth'e present invention and its use in connection with equipmentof this type.

Between the panel and the dial there is I interposed an element 8provided with a longitudinal sloti) designedto receive the shaft of theinstrument. This element is made of any sultable electrically,IlOII-COIlClLlCt-lVQ terial, preferably fibre. The element is providedwith three radial arms 11 of a length just slightly less than the radiusof the dial,

and a projection or extension 12 which exwhich they turn upwardly andalso by set-- ting-the dial nearer to or farther from the panel.

Adjacent theouter end of extension 12, a pin 13 is mounted upon thepanel. This pin is provided with a threaded aperture through whichextends a screw 14 designed to'impart a slow rotative movement to thefriction element 8. One end of this screw is provided with a ball 15which fits within a socket 16 on the upper end of a pin 17, mounted uponthe outer end of the extension 12. The other end of the screw isprovided with a head 18, polygonal in shape, the apices ofwhich, whenread in conjunction with a line 19 on the panel, indicate the degrees ofrotation of the screw.

To mount the precision adjusting device ofthe present invention upon apanel board of the ordinaryradio receiving set is a simple matter. Thedial of the instrument to be set is first removed andthe frictionelement 8 slipped over the shaft thereof. A hole is then drilled in thepanel and the pin 13 fixed in position. The arms 11 are bent upwardlyand outwardly a' slight degree and the dial then replaced and fixed uponthe shaft in such a position that the instrument can be turned by handwithout great diffi culty although the frictional engagement of the dialwith the friction element 8 should be reasonably stiff. This frictionalengagement should, of course, be sufiicient so that when the screw 14 isturned for precision adjustment, the dial will be moved, the frictionengagement of the arms 11 with the dial thus being sufficient toovercome any stiffness in the instrument mounting itself.

The operation of the device, although probably clear from the foregoingdescription may be briefly reviewed as follows The approximate settingis made with the lingers in the usual way and the fine adjustment byturning the screw 14 with the thumb or fingers through the head 18. Ifthe pin 17 is fixed upon the panel so that the movement of the screw isin a straight line, it is necessary to provide freedom for the element 8to slide slightly relative to the shaft 2, as well as rotating about it.The slot 9 is, therefore provided. This same result could, of course, beattained by permitting the pin 13 to have a slight rotative movement.The delicacy of the adjustment depends upon the length of the extension12 and the pitch of the screw 14, and these can, of course, be varied tosuit the requirements. So far as the'former is concerned, I have foundthat for radio work, the general proportions illustrated in the drawingsare satisfactory and I have used a screw having such a pitch that thehead 18 would make about six hundred (600) complete revolutions for onecomplete revolution of the dial 3. This device not only-gives a verydelicate 'ment having a dial forapproximate adjustments and a fixedpanel between the instrument and the dial, of a device for 1nakingprecision adjustments, comprising, a single element interposed betweenthe panel and the dial, making frictional engagement with the dial andextending beyond the periphery of the dial, and a screw mounted up onthe panel and operatively connected with the extension of the frictionmember to impart a slow rotative movement thereto.

2. A device for making precision adjustments of an instrument providedwith a dial for approximate adjustments and having fixed panel betweenthe instrument and the dial, comprising the combination of an elementinterposed between the dial and the panel and making frictionalengagement with the dial, a projection on the friction element extendingbeyond the periphery of the dial, a pin on the panel adjacent theprojection on the friction element, a screw threadedly mounted on saidpin, and an operative connection between the screw and the projection onthe friction element whereby as the screw is turned a slow rotativemovement is imparted to the friction ele ment and the dial.

3. A device for making precision adjustments of an instrument providedwith a dial for approximate adjustments and having a fixed panel betweenthe instrument and the dial, comprising the combination of an elementinterposed between the dial and the panel and making frictionalengagement with the dial, a projection on the friction element extendingbeyond the periphery of the dial, a pin on the panel adjacent theprojection on the friction element, a screw threadedly mounted on saidpin, a head on the end of the screw provided with means for indicatingits degree of rotation, and an operative connection between the screwand the projection on the friction element whereby as the screw isturned a slow rotative movement is imparted to the friction element andthe dial.

4. A device for making precision adjustments of an instrument providedwith a dial for approximate adjustments and having a fixed panel betweenthe instrument and the dial, comprising the combination of an elementinterposed between the dial and the panel and making frictionalengagement with the dial, a projection on the friction element extendingbeyond the periphery of the dial, a pin on the panel adjacent theprojection on the friction element, a screw threadedly mounted on saidpin, a ball and socket connection between the screw and the projectionon the friction element whereby as the screw is turned a slowrotativemovement is imparted to the friction element and the dial.

5. A device for making precision adjustments of an instrument providedwith a dial for approximate adjustments and having a fixed panel betweenthe instrument and the dial through which the shaft of the instrumentpasses, comprising the combination of an element interposed between thedial and the panel, having a longitudinal slot designed to receive theshaft of the instrument andha-ving outwardly-bent arms making frictionalcontact with the dial, a projection on the friction element extendingbeyond'the periphery of the dial, a pin on the panel adjacent theprojection on the friction element, a screw threadedly mounted on saidpin, and an operative connection between the screw and the projection onthe friction element whereby as, the screw is turned a slow rotativemovement is imparted to the friction element andthe dial.

In testimony whereof I afiix my signature.

EDWARD K. CURTIS.

